In order to appropriately collect information owned by terminals and the like through wireless communication, it is necessary to transmit and receive appropriate information between a transmission source and a transmission destination. For example, Patent Literature 1 discloses a technology which relates to information transmission between a master and a slave and automatically secures a substituent communication path between a master and some slaves thereof even in a case in which there is an obstacle between the master and the slaves that blocks synchronization therebetween. In the technology, the master regularly transmits a synchronization signal to each slave, and each slave returns a reception signal according to the reception of the synchronization signal to the master. In a case in which a reception signal corresponding to a synchronization signal has not been received for a predetermined time, the master determines that a slave associated with the reception signal is no longer visible and adjusts wireless transmission/reception such that a packet from the slave can be transmitted and received in a substituent path via another slave.
In addition, Patent Literature 2 discloses a technology in which, in a wireless communication network of a multi-hop type in which there is no master, each wireless device delivers time synchronization information to wireless devices having no established time synchronization due to presence of an obstacle between the wireless devices. More specifically, in a case in which information is to be transmitted from a certain wireless device (own device) to another wireless device, information relating to a time slot of the wireless device that is the own device is exchanged between detectable wireless devices before the transmission, and time synchronization for wireless transmission is established (a time slot for wireless transmission is determined). Accordingly, until the time synchronization is established, transmission and reception of a plurality of signals between wireless devices are necessary.